Seven decades ago this morning, the greatest invasion force in the history of warfare emerged from the darkness, rain and fog off the beaches of Normandy and methodically pierced the Atlantic perimeter of Adolf Hitler’s Fortress Europe — though at an epic price and to no certain outcome.

In the event, the Austrian madman’s Thousand-Year Reich would be gone in 11 months time, as well as the despot himself. Measured against that result, D-Day’s fearsome butcher’s bill seems reasonable, if not modest.

It didn’t appear so at the time, of course — not at sea off the French coast, not in the air over the battlespace and certainly not on the five invasion beaches themselves.

Twenty-four Allied warships would be destroyed on D-Day, and 35 merchant vessels.

In the two months before the invasion, some 2,000 Allied combat aircraft — and 12,000 aircrew — had been lost in the effort to ensure, among other things, that the once-commanding German air force would be no factor when the landings began. It wasn’t.

And then there was the landing force.

Roughly 150,000 men, including three airborne divisions, crossed the beaches on D-Day and the hours immediately following.

They met resistance ranging from minor to murderous — war can be a cruel lottery — and while not every man was a hero, from a distance of 70 years it fairly can be said that every man did his duty.
The Atlantic Wall was breached, at a cost of 4,400 Allied lives, including those of 2,500 Americans.

Three of the four Medals of Honor awarded for D-Day gallantry came posthumously — as is usually, sadly, the case.

Yet the most vicious fighting for Normandy was still to come: It would be weeks before the Allies broke free of their tenuous beachheads and began the long bloody slog to the Rhine and beyond.

Such heroism. But who really remembers?

The youngest survivors among Dwight Eisenhower’s crusaders today are approaching 90; soon, they too will be gone — and who will then bear witness?

Well, today a new memorial to those who served in America’s armored forces during the European campaign will be dedicated on Long Island.

The American Armor Museum at Old Bethpage comprises a modest, fully operable collection of World War II-era combat vehicles built around a copy of Americans main battle tank of the era — the iconic M4 Sherman.

A visit would be an educational experience — which is as it should be — but there is much more to it than that.

The museum, says founder Lawrence Kadish, “has never been about the tanks but about the men who drove them” — that is, the men whose courage and sacrifices the nation will celebrate today — “[and] it is about honoring all those Americans who have served and those who continue to be on the front lines.”

This seems right.

There will never be another ­D-Day. Satellite surveillance, drone technologies and arsenals bulging with smart weapons — some with nuclear warheads — conspire to render the great set-piece battle as obsolete as horse cavalry. And that’s no tragedy.

So Kadish is correct to suggest that today’s focus should be at least as much on the warriors as it is on their weapons — which, in any event, evolve over time to meet ever-changing threats.

Seventy years ago, that threat was Adolf Hitler and Tokyo’s warlords. Then came Josef Stalin and the Cold War.
Today it is terrorism — and, as Kadish succinctly puts it, “No one has signed an armistice in this conflict, and we very much remain a nation at risk from a cruel and relentless enemy.”

But tomorrow, what?

It’s not hard to see the dark shadows: Vladimir Putin’s ambitions; a restive China, anxious to put its mark on the South China Sea and East Asia in general; a brewing hot war in the Middle East.

Washington seems befuddled by all this, as it has in the past — and lacking in purpose, too, which also is nothing new.

But while irresolution always beckons needless trouble, America’s enemies might want to ponder this:
The remains of 9,386 American soldiers and airmen rest in the military cemeteries of Normandy — silent testimony to the courage and determination a great nation once brought to an existential struggle with boundless evil.

When it mattered, America mattered.

Whether it will again is by no means certain — but it is a foolish man who would bet otherwise.